Black & Yellow

Another quick week has gone by and we’re on the road again from Kejimkujik to Prince Edward Island. Famed for its mosquitos, clear night skies and Mi’kmaq origins, Kejimkujik National Park did not fail to impress. In an act of sublime timing and luck we were able to arrive in one of Canada’s most ideal spots for night sky viewing during the incredible Perseid meteor shower. For three days the sky was periodically streaked with ephemeral cosmic lights and we soaked up every bit of it we could. Our days were filled with frogs, deer, the occasional snake and of course many an arthropod.

Agriope aurantia female consuming her Orthopteran prey

One arthropod in particular caught my interest: an arachnid, the Black and Yellow Garden Spider, Argiope aurantia. We had just about completed one of our hand collection events at the Farmlands trail (hand collecting is when we travel down a path and manually collect arthropods along the way) and came into a clearing where a farm once stood. In a lone bush among the tall grass that now dominated the clearing was the strikingly large Argiope aurantia, where it carefully maintained and monitored its web. The web was also the final destination for a number of unfortunate grasshoppers and flies.

As is true with many spiders, there is a distinct sexual dimorphism observable in the relative size of the males and females. The A. aurantia I photographed was clearly a female with a body length well over an inch; their male counterparts are often three times smaller than the female. The distinct yellow markings against black background on the abdomen remain conserved between the sexes, making for a relatively easy identification.

Note the distinctive markings on the abdomen and the white, hairy cephalothorax.

A female Black and Yellow Garden Spider will spend the majority of her life within a small range, generally staying within her web for the entire summer where she will eat, mate and lay eggs. The smaller male will construct his web either within or adjacent to the female’s web. There is no ambiguity to the male’s purpose in this relationship, after he mates he will die and potentially be consumed by the female. The female will lay thousands of eggs within several sacs encased in layers of silk. She will spend the remainder of her summer and life protecting the eggs; eventually she will die come the frost. The eggs will overwinter and emerge the next year.

Despite the size and intimidating appearance, these spiders pose no threat to humans. They have a large range with populations in Canada, the United States, Mexico and Central America.

Relationships with Fungi

Relationships with Fungi

Val (our crew chief) recently tweeted about the huge variety of fungi in Cape Breton Highland, and Kejimikujik was not different! Everywhere we went we saw a variety of different types of fungi. It was only then that I realized that fungi are undervalued by most passerbys. Fungi, whether they look like the familiar mushroom cap, the shelf-like tree outgrowths, or the many types of mould, are fundamental parts of a healthy ecosystem. Without fungi organic matter would accumulate on the forest floor and nutrients would not be available to promote growth.

Fungus beetle feasting on a mushroom in Keji

One surprising feature is that the typical mushroom cap is usually only a small outcropping of the entire organism. Mushrooms are actually only the reproductive outgrowths from an intricate interwoven network of hypha that travel through the soil. The gills or lamellae on the underside of mushroom caps can produce up to 1 800 million spores per mushroom cap, each of those spores are capable of creating more hyphae, which can then create innumerable mushroom caps. In short- there’s a lot more than meets the eye.

Fungi can have a number of different relationships with surrounding plants such as trees. Parasitic fungi can overwhelm a tree, causing the tree to die and will then continue to decompose the fallen tree. Many of the parasitic species are introduced to trees by the actions of our lovely insects. Fungi can also have a beneficial relationship with trees where the hyphae stimulate tree growth by increasing the absorption area of the roots, and in return the hyphae obtain sugar directly from the host (rather than through decomposition).

Hemlock shelf fungi are slowly decomposing this stump

Even more interesting are the intricate relationships of insects and fungi. Like trees, fungi can be a huge nuisance for the insect, or even completely alter the insects’ normal behavior. In the latter case, is a well-documented case of proclaimed “zombie-ism”. The Ophiocordycep fungi attach the brain of afflicted ants, causing them to abandon their colony and latch onto main vascular vein on the underside of a leaf. The fungi then lives in the plant and cycles through to parasitize more ants. Entopathogenic fungi will live inside of the cuticle of insects before killing its host by penetrating the body cavity.

Of course you can also find instances of beneficial relationships between the crawling world and fungi. We commonly found rove and fungus beetles feasting on the mushroom caps of fungi, and many insects have been known to have even more involved relationships. Female scale insects often live inside of fungi where they benefit from having shelter from the environment, protection from predators and have close proximity to their food source (such as trees). In return, the fungi have a specialized feedings hyphae that enters the insect and uses it as a sugar-pumping conduit from the tree.

In exceptional cases, such as with termites and leaf cutter ants, the insects actually farm the fungi! They will provide food for the fungi, even weed out species of fungi that they don’t want, before eating their cultivated crops. There are numerous more examples of mutualism between both fungi and insects that are very interesting! (for instance look up scolytid beetles) Much like the underground network of hyphae, fungi have connections all through ecosystems ranging from plants, to insects, and even to larger animals. Without these little appreciated organisms we can very well expect that much (if not all) life that we see would collapse.